The present invention relates generally to the presetting of ignition timing for internal combustion engines and more particularly to an ignition timing method and apparatus adaptable to a number of different ignition systems on otherwise substantially similar engine arrangements requiring a minimum number of components peculiar to the particular ignition arrangement.
In the world of small internal combustion engines, it is commonplace to encounter ignition arrangements having one portion rotatably supported on an engine flywheel with another ignition portion fixedly supported by the engine and in close proximity to the flywheel supported portion. The same basic engine may be manufactured and sold with several different ignition options or one ignition arrangement may be obsoleted by an improved ignition, in each case requiring some parts peculiar to the particular ignition system employed. From a manufacturing as well as from a spare parts supply point of view, the number of parts peculiar to a particular ignition system should be minimized.
Exemplary flywheel ignition arrangements for small internal combustion engines are illustrated, for example, in U.S. Pat. Nos. 3,490,426 and 3,952,712, wherein a flywheel has a permanent magnet or a section of ferromagnetic material disposed in a certain region of its periphery and closely adjacent thereto a fixed ignition coil arrangement is supported on the engine, for example interior of the flywheel periphery, so that as the flywheel rotates, carrying with it the ferro-magnetic or permanent magnet segment, that segment repeatedly passes the ignition coil inducing a voltage therein for ultimately providing the ignition spark at an appropriate time in the engine cycle. Timing for such exemplary systems may of course be changed by physically displacing the fixed ignition coil, however, such physical displacement is often inconvenient and sometimes impossible.